Apparatus and method for refrigeration by carbon dioxide



NOV 5, 1963 H. v. WILLIAMSON ETAL 3,109,296

APPARATUS ANO METHOD FOR REFRIGERATION BY CARBON DIOXIDE INVENTORSH/LD/Nc; l/. W/L/AMsoA/ Qu BY AA/a CLARENCE E. WOLFE Tom/EY H. v.WILLIAMSON ETAL 3,109,295

APPARATUS AND METHOD FOR REFRIGERATION BY CARBON DIOXIDE s sheets-sheet2 Nov. 5, 1963 Filed Sept. 29, 1961 BY CLARE/v0.55. Wou-'e Smmlllll.IIIIIII u n n l l l n l l L Nov. 5, 1963 H, v. WILLIAMSON ETAL3,109,296 APPARATUS ma METHOD RoR REFRIGERATION BYl CARBON DIoxIDE Filedsept. 29, 1961- 5 Sheets-Shea?. 3

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Arrow/EY United States Patent O 3,109,296 APPARATUS AND l/iETl-ID FQRREFRGERA- TIN BY CARB'GN DIOXlDE Hiiding V. Williamson, Chicago, andClarence E. Wolfe, Hinsdale, Ill., assignors to Chemetron Corporation,Chicago, lll., a corporation of Delaware Filed Sept. 29, 1961, Ser. No.141,745 11 Claims. (Cl. 62-'76) This invention relates to an apparatusand to a method for refrigeration, and more specifically to an apparatusand method for refrigerating a compartment by spraying liquid carbondioxide thereto.

The invention has particular utility in the refrigeration of transportcompartments such as insulated railroad cars and motor trucks forhighways, and including compartments of trailers adapted to betransported crosscountry on railroad cars and then to be transportedlocally by motor truck or tractor. Moreover, the present invention issuitable for refrigeration of compartments of motor trucks used to makelocal deliveries of refrigerated goods such as frozen foods, meat andice cream. Continued opening of the refrigerated compartments for localvdelivery of frozen foods and the like on a wholesale or retail levelpresents particular diiliculties in maintaining the goods in the properstate of refrigeration.

Mechanical refrigeration systems have been used for the refrigeration oftransport compartments, but difficulties arise in maintaining continuedoperation thereof because of the complexity of the system. Additionally,the high initial cost of such equipment has made it questionable formany applications. Although ice formed of water has been used as arefrigerant r coolant of transport compartments, water-ice as arefrigerant has the disadvantages of requiring re-icing during a longjourney and of requiring a large ice load, thereby decreasing the usablepayload that can be carried. Moreover, the temperature which can bemaintained in the refrigerated compartment is limited with the use ofwater-ice.

The use of liquid nitrogen has heretofore been proposed as a refrigerantbut because of the low temperature necessary to maintain the nitrogen inliquid state, the storage facilities for liquid nitrogen are complex andexpensive and generally require a jacketed powdervacuum insulatedstorage vessel. Moreover, nitrogen is not always available commerciallyin all locations. Carbon dioxide has heretofore been used as arefrigerant, forming the well-known Dry lce in its solid state. WhileDry Ice makes a desirable refrigerant for many applications, it requiresmanual handling which becomes difiicult because of the tendency for theDry ice to cause burning when it comes in contact with the human hands.Carbon dioxide in the liquid state as a refrigerant has generallyrequired the use of heat exchangers with accompanying complexity of thesystems and initial high cost thereof.

According to the present invention, liquid carbon dioxide sprayed intothe refrigerated compartment makes a desirable refrigerant. However,carbon dioxide cannot exist in the liquid state at atmospheric pressure,but only in the solid or lgaseous state. Carbon dioxide exists in theliquid state only at pressures above the triple point, or about 75 lbs.per square inch absolute. Accordingly, there is a tendency for liquidcarbon dioxide to solidify while being sprayed into a refrigeratingcompartment, thereby preventing proper functioning of the refrigeratingsystem, and specifically of the spray nozzles thereof, unless the carbondioxide is quickly passed through the triple point. Moreover, additionaldifficulty arises because the carbon dioxide system may be used intrailers carried by railroad cars and other transport applications whereelectrical power for control may not be available.

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Patented Nov. 5, i963 ICC It is therefore an object of the presentinvention to provide an improved refrigeration system.

A further object of the present invention is to provide an improvedrefrigeration system which overcomes the above-mentioned difficulties. 1

A further object of the present invention is to provide an improvedrefrigeration system which is particularly advantageous for use intransport compartments of motor vehicles, railroad cars, and the like.

Yet a further object of the present invention is to provide an improvedrefrigeration system which is low in initial cost and economical tomaintain and operate.

Still a further object of the present invention is to provide animproved refrigeration system that does not reuire electrical power tooperate or control the same.

A further object of the present invention is to provide an improvedrefrigeration system operating on liquid carbon dioxide. y

Still another object of the present invention is toy provide an improvedrefrigeration system for spraying liquid carbon dioxide in arefrigerating compartment.

A further object of the present invention is to provide an improvedmethod of refrigeration.

And still another object of the present invention is to provide animproved method of spraying carbon dioxide into a refrigerat-ingcompartment.

Briefly stated, the invention is directed to an apparatus and method forrefrigeration of compartments by spra ing liquid carbon dioxide withinthe compartment. The improved refrigeration system is particularlyadapted for cooling the refrigerating compartment of transport vehicles.ln accordance with the invention, the discharge of liquid carbon dioxidefrom a supply tank containing liquid carbon dioxide under pressure isautomatically controlled. The pressure of the vapor in the carbondioxide tank is used to keep a liquid discharge valve closed thereby toprevent the discharge of the liquid carbon dioxide refrigerant into thecompartment when the temperature in the compartment is below apreselected level. A temperature sensing device actuates a vaporcontro-l valve which releases the vapor pressure and allows the liquiddischarge valve to open and the liquid refrigerant to be sprayed intothe compartment.

A quick-acting liquid discharge valve is provided so that the liquidcarbon dioxide in the space between the valve and the spray nozzle -isquickly moved through the triple point thereby minimizing thesolidilication of the carbon dioxide in the system. ln accordance withone embodiment of the invention, the valve is a pneutmatically actuatedquick-acting valve which includes a pressure differential responsivemeans and a portion lof one side of the pressure differential responsivemeans forms a valve portion which is seatable against a va-lve seatopening in the body of the valve. The liquid carbon `dioxide is placedin communication with one side of the pressure responsive means and theother side of the pressure responsive means is in communication with thevapor `in the carbon dioxide tank. A lloW restricting plug is positionedfin the carbon dioxide vapor l-ine leading to the valve. The pressure`differential responsive device is therefore controlled by the pressureof the liquid carbon dioxide `on `one side thereof and bythe pressure ofthe carbon dioxide vapor on the other side thereof. The scarbon dioxidevapor is bled off the valve in response to the temperature within therefrigerating compartment to cause the pressure differential responsivemeans in the valve to actuate the valve and to move the valve portionrelative to the valve seat opening to open and close the valve. iIt willbe appreciated that when the valve portion is seated 4against the valveseat, the pressure of the carbon dioxide liquid on the yone side of thepressure responsive means acts only on the difference between thecross-sectional area of the pressure responsive means and the area ofthe seat opening while the pressure of the carbon dioxide vapor on theopposite side of the pressure differential responsive means -acts on theent-ire crosssectional `area thereof to rforce and maintain the valve ina closed position. However, once the valve begins to open, that is, asthe valve portion rises oil .the valve seat opening, the force of theliquid carbon dioxide on the one side of the pressure differentialresponsive means is applied to the entire cross-sectionalarea of thepressure responsive means and, accordingly, results in a quick snap--acting valve opening.

The instant invention is also directed to the method of spraying liquidcarbon dioxide into `a compartment. The method of the present inventionis carried out by storing a quant-ity of liquid carbon dioxide underpressure, and periodically discharging a portion of the liquid carbondioxide into the refnigerating compartment in response to thetemperature .in the compartment. 'Ihe discharge of the liquid carbondioxide into the compartment is rapidly initiated to begin .thedischarge and is rapidly terminated to end the discharge, therebyquickly bringing the carbon dioxide liquid through the triple point andpreventing the formation of solid carbon dioxide. The pressure of thecarbon dioxide lliquid and the carbon dioxide vapor is utilized 4toinitiate and terminate the discharge.

The invention together with additional objects and advantages will bestbe understood from the following description of specific embodimentsthereof, 'when read in connect-ion with the accompanying drawings, inwhich:

FIG. l is a somewhat schematic, partly sectional View, of a refrigeratedtransport compartment equipped with the new refrigerating systemaccording to the present invention;

FIG. 2 is a fragmentary, partly sectional view, of certain components ofthe refrigerating system according to the present invention;

FIG. 3 is a cross-sectional View of one of the system components, takenalong line 3 3 of FIG. 2, and assuming .that FIG. 2l shows the entirecomponent;

FIG. 4 is a cross-sectional view of one component of the system, :takenalong line 4 4 of `FIG. 2, and assuming that FIG. 2 shows the completecomponent;

FIG. 5 is a cross-sectional view of a modied temperature responsivecontrol valve .for use in an limproved re-frigerating system accordingto :the present invention;

FIG. 6 is a cross-sectional -view of .the valve of FIG. 5, taken alongline V6-6 thereof, and assuming that FIG. 5 illustrates the entirecontrol Valve;

FIG. 7 is a fragmentary, cross-sectional view of the valve of FIG. 5,illustrated in another of 4its operating portions;

FIG. 8 is a cross-sectional View of a liquid carbon dioxide dischargevalve and nozzle according to another embodiment of the presentinvention; and

FIG. l9 is a cross-sectional View of a temperature responsive controlaccording to `another embodiment of the present invention.

Referring now Ato the drawings, and particularly to the embodiment ofFIGS. l to 4 thereof, there is illustrated a refrigerated transportcompartment lilv equipped with an improved refrigerating system 11according to the present invention. The transport compartment 10 maycomprise the body of a highway truck or trailer, or of a railroad car,or other transportation medi-urn. The transport compartment 1i?9 isadapted for carrying and transporting crates or other packages of frozenfood, meat, ice cream and similar refrigerated items 12.

In order to provide liquid carbon dioxide for the refrigerant, thesystem 11 includes a tank or pressure vesse 13 containing liquid carbondioxide 14 under pressure. In rorder to maintain the carbon dioxide 1din the vessel 13 yliqueied, vthe pressure within the tank 13 must begreater than the triple point, i.e., greater than about lbs. per squareinch absolute. A pressure range extending from about to about 300 lbs.per square inch absolute 'is considered to be a satisfactory pressurerange for the present invention. The lower portion of this range isdesirable because of the increase in the re- :frigerating etect or"liquid carbon dioxide with decrease in pressure. tion, the vessel -13was ii-lled with liquid carbon dioxide 14 at a pressure of about 250lbs. per square inch absolute. A liquid carbon dioxide supply conduit 15extends into the vessel 13 below the level of the liquidV carbon dioxide14 within the vessel 13. It 'will be appreciated that the space above`the liquid carbon dioxide 1d in the vessel 13 is .lled with carbondioxide vapor 1e or carbon dioxide in the gaseous state due to the vaporpressure of the liquid carbon dioxide. A vapor conduit 17 communicateswith lthe carbon dioxide vapor 16. The vessel 13 is additionallyprovided with a safety pressure relief valve 20 extending externally ofthe compartment 1G and a ller line 21 and tiller valve 22, alsoextending externally of the `transport compartment 10. The -vessel 13 isalso provided with the usual pressure equalizing line (not shown) forconnecting the vapor space of vessel 13 with the vapor space of a supplyvessel (not shown) during a iilling operation.

The walls of the transport compartment 1d may be provided with suitableinsulation material as required by the temperature desired within thecompartment. Similarly, the walls of the vessel 13 may be provided withsuitable insulating material. Where the pressure vessel 13 is placedwithin the transport compartment 10 and the compartment 10 is operatedat approximately 0 F., or less, the vessel may be installed as shownwithout insulation. Insulation is preferably applied to the pressurevessel 13 if the operating temperature in the compartrnent 10 containingthe vessel is to be higher, such as 40 F., as may be required forcertain types of lading. Of course, the pressure vessel can also beinstalled outside of the refrigerated transport compartment 10; in sucha case it should be Well insulated in order to avoid loss of efficiencyby heat from outside air.

As a means of spraying the liquid carbon dioxide into the compartment10, there is provided a spray nozzle or plug 23 which communicates withthe liquid carbon dioxide 14 in the vessel 13 through a liquid carbondioxide discharge control valve 24 and the supply conduit 15. As is bestillustrated in FIG. 2, the discharge control valve 24 includes a valvebody or housing 24a having an expandable valve or liquid chamber 2411for liquid carbon dioxide. A liquid discharge port or valve seat opening25 and a liquid inlet port 33 extend through the housing 24a andcommunicate with the liquid chamber 24h. The spray nozzle 23 is providedwith external threads 27 received in internal threads 26 in the liquiddischarge port 25. An axial passageway 3)v extends through the spraynozzle 23 and the passageway 30 forms a metering oriiice 31 at its outerend to provide a spray 32 of liquid carbon dioxide as illustrated inFIG. l.

The discharge control valve 24 controls the periodic discharge of liquidcarbon dioxide through the spray nozzle 23 as required to maintain thedesired temperature in the compartment 10. The discharge control valve24 is pneumatically operable, and, as shown, is actuatedV by thepressure of the liquid carbon dioxide 14 to bias the valve into an openposition, and by the carbon dioxide vapor 16 in the pressure vessel 13to bias the valve closed. Moreover, the valve 24 is of the quick-actingtype so that the volume of liquid carbon dioxide between the valve andthe metering orifice 31 is rapidly transferred from the high supplypressure to the pressure of the compartment 10, passing quickly throughthe triple point pressure so that solidiiication of the liquid carbondioxide does not occur within the spray nozzle 23.

The discharge control valve 24 in the illustratedem- In one embodimentof the present inven-A Y bodiment includes a valve stem assembly 3dformed with a valve stem 34a provided with a resilient disk or valveportion 36 at one end which is seatable against a valve seat 37 formingthe liquid discharge port 25. In order to move the resilient disk 36relative to the valve seat 37 to close and open the liquid dischargeport 25, the valve stem 34a carries a pressure differential responsivemeans, here shown as a bellows di) having its edges sealed to thehousing 24a and forming a movable wall of the chamber Zlib. The bellowsdi) also form a wall of an expandable carbon dioxide vapor chamber 42for receiving carbon dioxide vapor. A disk or piston 43 is positioned onthe end of the valve stem 34a to center the bellows 49 within the valvehousing 24a. The stem 34a extends into a guide bore 38 in the housing24a to further center and mign the valve stem assembly 34 with the vaporchamber 42. A plurality ot vapor passageways 39 extend through the valvestem 34a interconnecting the vapor chamber 42 and a Vapor port 4S. Avapor conduit 46 is connected to the vapor port 45 and the conduit 17 tointerconnect the vapor chamber 42 and the vessel 13 to provide carbondioxide Vapor to the vapor chamber 42. The resilient disk 36 forms anend portion of the pressure differential responsive means 4t), therebyreducing the effective cross-sectional area of the bellows lil when thedisk 35 is seated against the valve seat 37. A compression spring 44positioned in the vapor chamber 42 is eiective to bias the bellows d@ toa valve closed position as illustrated in FIG. 2.

ln operation, brieily, carb-on dioxide Vapor is supplied to the vaporchamber 42 of the valve 24 through the vapor conduit i7, vapor port d5,and passageways 39. With the valve 24 in the closed position illustratedin FIG. 2, the pressure of the liquid carbon dioxide in the liquidchamber Ztb will act on the pressure diierential bellows 4t? on aneffective tarea equal to the cross-sectional area of the lbellows 49,less the cross-sectional area of the valve seat opening 25; the pressureof the carbon dioxide vapor in the chamber 42 will always act lon anetective area ot the bellows d@ equal to the cross-sectional area of thebellows 4t?. If the carbon dioxide vapor is 1bled from the vapor chamber42, the pressure of the liquid carbon dioxide in the liquid carbondioxide chamber 24h will be effective -to raise the resilient disk 36from the valve seat 37 against the return :bias of the carbon dioxidevapor in the vapor chamber 4Z and the return bias of the spring 44. Oncethe resilient disk 36 has lifted from the valve seat 37, the pressure ofthe liquid carbon dioxide now acts over the entire crosssectional areaof the bellows 40, including the cross-sectional area of the valve seatopening 25, and the valve 24 is quickly opened with a 'snap action dueto the increased edective cross-sectional area of the bellows 40 -to theliquid carbon dioxideln order to close the valve 24, the pressure in thevapor chamber 42 is permitted -to build up to approximately equal thatof the pressure of the liquid carbon dioxide in the valve chamber Zeb.Once the pressure of the liquid carbon dioxide `and vaporous carbondioxide balance each other on respective -sides of the bellows 4t), thespring 44 is effective to bias the resilient disk 36 toward a valveclosing position against the valve seat 37. However, as the resilientdisk 36 appreaches the valve seat 37, the effective cross-sectional areaof the bellows 4i) exposed to the liquid carbon dioxide is reduced bythe cross-sectional area of the valve seat opening 25 and therestraining force on the bellows 40 is accordingly reduced by aproportionate amount. Consequently, the vapor pressure in the vaporchamber 42 is eie-ctive to rapidly close the valve 24 with v'a snapaction.

ln order to permit the vapor in the vapor chamber 42 to be bled `fromthe valve 24, the vapor conduit 17 is provided with a now-restrictingmeans 47, here indicated as a coupling enclosing a porous plug (notshown) having a restrictive passageway therethrough. It will 'beunderstood that other types of ow restriction devices such as anorifice, a needle valve, la capillary tube in place of conduit 17, etc.,may be used to perform the function of flow-restricting means 47. Theflow-restricting means 47 permits the carbon vdioxide vapor 16 in thevapor chamber 42 to be selectively withdrawn more rapidly thanadditional lvapor can be supplied thereto through the dow-restrictingmeans 47, thereby to .reduce the vapor pressure in lthe vapor chamber42.

Withdrawal of carbon dioxide vapor from the vapor chamber 42 iscontrolled by a temperature responsive control means including atemperature sensing device 48 and temperature responsive vapor controlvalve 50. The temerature sensing device 48 includes a body or housing 49containing a iluid filled bellows 5l connected to a lluid filled bulb S2through suitable tubing 53. The lluid filled bulb 52 is exposed to theambient temperature inthe transport compartment lil and the uid in thebulb 52 exands and contracts in response to temperature changes withinthe compartment 1t?. Speciiically, as the temperature in the compartment1l) increases, the uid in the builb 52 expands and is pushed into thebellows 51 which then is forced to expand or elongate. As the bellows 51expands, it pushes against a thrust pin 54 in the housing i9 of thetemperature sensing device 48.

The vapor control valve Sil includes a valve body or housing 56 forminga valve chamber 50a. A needle valve 55 within the valve chamber 50a isbiased against a valve seat 57 forming a vapor discharge port S8 andcommunieating with the atmosphere or compartment l0 through an exhaustopening 61. A compression spring 62 in the chamber 50a is positioned tobias the needle valve S5 into a valve closed position. As bestillustrated in FIG. 4, the needle valve is of generally square crosssection, rounded at its corners, so as to provide a plurality ofpassageways 63 around fthe needle valve S5 through the valve chamberSila. The Valve chamber 50a is provided with a vapor inlet passageway 65which communicates with the vapor chamber 42 in the discharge controlvalve 2d through a vapor conduit 66 and the conduit 46. The

thrust pin 54 extends through the vapor discharge port 58 to engage theneedle valve 55. Expansion of the bellows 51 due tto a temperature risein the compartment 1t) is elective to move the thrust pin 54 to unseatthe needle valve 55, and thereby bleed the vapor from the vaporcompartment 42.

In order to provide .for manually turning the refrigeration system ll onand oit When :the 'transport vehicle carrymg the compartment 10 is inuse or is sitting idle, the vapor conduit 66 leading from the vaporcontrol valve Si) to the discharge control valve 24 is providedwith amanually controllable shutoi valve 70, FIG. 1. When the valve 7d isclosed, carbon dioxide vapor cannot be bled from the gaseous carbondioxide chamber 42 and the build-up of vapor pressure through theconduit 17 and the dow-restricting means 47 into the vapor chamber 42Will close 'the discharge control valve 24.

For adjusting the temperature in the compartment lll, the thrust pin 54and lthe bellows 51 of the temperature sensing device 48 are selectivelypositionable relative to the vapor control valve S0 to vary the amountor" bellows expansion required to unseat the needle valve 55 through thepin 54. This is readily accomplished in the embodiment of FIGS. l to 4by providing the housing 56 of the vapor control valve Si)y with aninternally threaded bore '71 axially aligned -with the needle valve 55,and providing the housing 4-9 with an externally threaded projection 72threaded into the bore 71. The thrust pin 54 extends through an opening72a in the projection 72 into Ithe vapor discharge port 58 to engage theneedle valve 55'. The relative positions of the temperature sensingdevice 48 and vapor control valve 50A are locked by a lock'nut 73.Threading the housing yi9 ofV the temperature sensing device 43relatively outward of the housing 56 of the vapor control valve Si@results in moving the bellows 51 and associated thrust pin 54 furtheraway from the needle valve 55 so that a greater expansion of the bellows51 is required to unseat the needle valve 55 and, accordingly, a highertemperature will be required in the compartment *10 in order to actuatethe vapor control valve 50 to bleed the carbon dioxide Vapor from thedischarge control valve 24.

From fthe above-detailed description, the operation of lthe improvedrefrigeration system is believed clear. However, briefly, it will beappreciated that if the carbon dioxide vapor is bled from the vaporchamber 42, the pressure of :the liquid carbon dioxide in the expandablevalve chamber 241; will be effective to over-ride the restraining forceof the carbon dioxide Vapor in the vapor chamber 42 and the return biasof the spring 44 to open the valve 24 by lifting the resilient disk 36from the valve seat 37 thereof. Moreover, due to the sudden change inthe effective area of the bellows 44D when the resilient disk 36 isseated on the valve seat 37 and when the resilient disk 36 is liftedfrom the Valve seat 37, once opening or closing of the valve 24 hasbegun, the opening and closing will thereafter be accomplished quicklyand positively.

When it is desired to start up the refrigeration system Iii, themanually controlled shutod valve 7S` is opened so that the vapor chamber42 is placed in communication with the vapor control valve chamber 59a.lf the ternperature in the refrigerator compartment lo is above thepreselected temperature adjustment of the temperature sensing device 43and vapor control valve 58, as determined by the relative positioning ofthese components through the threaded connection of projection 72. andbore 71, the fluid in the fluid lilled bulb 52 will be expandedsuiliciently to expand the iluid illed bellows l causing the thrust pin54 to hold the needle valve 55 unseated from the valve seat 57. In 'thisposition, the vapor chamber 42 is placed in communication with theinterior of the compartment 10 through the conduits 46 and 66, the vaporinlet passageway 65, the valve chamber Sila including the passageways`63, the vapor discharge port 5S, and the exhaust opening 6l. Althoughcarbon dioxide vapor 16 will continuously pass through theflow-restricting means 47, such vapor will be exhausted through -theaforementioned exhaust opening 61 and vapor pressure lwill not build upin the vapor chamber 42. Liquid carbon dioxide 14, on the other hand,`will be transported to the valve chamber 24h through the conduit 15 andwill act on the bellows `461 to be effective tolift the resilient disk36 from the valve seat 37 in the abovedescribed manner. The liquidcarbon dioxide will then be discharged as a spray through the meteringoriiice 31 of the spray nozzle 23 and will cool the refrigeratedcornpantment 1G.

As soon as the temperature of the compartment 10 has been brought downto the preselected level, the tiuid in the fluid filled bulb 52 willcontract, permitting the bellows 51 to contract. The compression spring62 will be effective to bias the needle valve 55 against the valve seat57 and to terminate the exhaust of carbon dioxide vapor through theexhaust opening 61. With the exhaust of the carbon dioxide vaporterminated, the pressure in the vapor chamber 42 will begin to build up.as a result of the vapor which is ltering :through the dow-restrictingmeans 47 and when the pressure in the vapor chamber 42 approaches thepressure of the liquid carbon dioxide in the valve chamber 24h the valvestem assembly 34 will be driven into a valve closed position by thecompression spring 44 and will operate rapidly and positively as aresuit of the reduction in the effective area of the bellows 40 as thedisk 36 approaches the valve seat 37.

In accordance with the Vimproved method of spraying liquid carbondioxide into a refrigerated compartment 10, the invention is carried outby storing a quantity of liquid carbon dioxide 14 under pressure abovethe triple point of approximately 75 lbs. per square inch absolute, forexample, at a pressure in the range of 150 to about 300 lbs. per squareinch absolute. The liquid carbon dioxide is supplied to a dischargenozzle 23 for discharge into the refrigerated compartment 1 in responseto the temperature changes in the temperature sensing device 48. Aportion of the liquid carbon dioxide is periodically `discharged intothe compartment 16 under the control of the discharge control valve 24.Because of the rapid change in the effective area of the pressuredifferential responsive bellows 40, the discharge of the carbon dioxideis rapidly initiated when the vapor pressure in the vapor chamber 42 isreduced to -a level wherein the pressure of the liquid carbon dioxide issuiic-ient to unseat the resilient disk 36 from the valve seat 37.Similarly, the discharge of liquid carbon dioxide 14 through the spraynozzle 23 is rapidly terminated due to the change in the eltective areaof the bellows 40 as soon as the resilient disk 36 is biased toward thevalve seat 37 by the building up of the vapor pressure in the vaporchamber 42 to approximately the same pressure as the liquid carbondioxide, thereby permitting the compression spring 44 to bias the valvestem assembly 34 toward a closed position. The rapid initiation andtermination of the discharge of the carbon dioxide is elected by theutilization of the pressure of the carbon dioxide liquid and the vaporpressure of the carbon dioxide vapor. The diierence obtained in fthevapor pressure and the liquid pressure of the carbon dioxide lis appliedto opposite sides of the pressure differential responsive device 40under the control of the temperature sensing device 48 and the vaporcontrol valve 50.

ln the above-described embodiment, the operating temperature or thetemperature at which the vapor control valve 5i) begins to open isadjusted by means of the threaded connection between the temperaturesensing device 48 and the vapor control valve 60 and then locked inposition with the lock nut 73. FIGS. 5 to 7 illustrate an embodiment ofthe present invention wherein the operating temperature for thetransport compartment may be more readily lield adjusted. Similar pantsof the sys-tem of FIGS. 5 to 7 and of the system of FIGS. l to 4 arerepresented by the same reference characters. FIGS. 5 -to 7 illustrate atemperature sensing device 48' provided with a housing 49 and includingthe iluid iilled bellows 51 connected to a Huid lled bulb (not shown)through suitable tubing 53. As heretofore described, the fluid filledbulb is exposed to the ambient temperature in the refrigeratedcompartment and fthe fluid in the bulb expands and contracts in responseto temperature changes within the compartment. As the bellows 51expands,` it pushes against a thrust pin 54 in the body 49' ofthe'temperature sensing device 48.

There is provided an associated vapor control valve 59 including theneedle valve 55 within a valve chamber 50a of a valve body 56' andbiased against the valve Yseat 57 forming a vapor discharge port 58. Thecompression spring `62 is eiective to bias the needle valve 55 into aclosed position.

For adjusting `the temperature in the refrigerating compartment, thethrust pin 54 of the temperature sensing device 48 is selectivelypositionable relative to the vapor control valve Sii' to vary theexpansion of the bellows required to unseat the needle valve 55 throughthe pin 54. In the embodiment of FIGS. 5 to 7, this is readilyaccomplished by providing for axial adjustment of the thrust pin 54 andneedle valve 55 by providing -an axial aperture 74 in the vapor controlvalve 5t) and an associated projection 75 on the body 49' of thetemperature sensing device 48' and slidably positioned within theaperture 74. Relative movement of the projection 75 into the aperture 74-is effective to regulate the amount of bellows expansion necessary tounseat the needle valve 55. The temperature sensing device 48 and theVapor control valve 50 are held in accurate position by a camarrangement including a temperature setting cam shaft '76 having alignedbearing portions 76a iournaled in aligned apertures 77 in the body 56'.The bearing portions 76a are interconnected by an eccentricallypositioned cam portion S passing through a cam follower slot 81 in thevalve body 49 of the temperature sensing device 48. The shaft isprovided with a suitable temperature selecting knob (not shown) toprovide for manual rotation of the shaft 76. A compression spring 82biases the temperature sensing device 43 and the vapor control valve 50'away from each other. k

In operation, the cam portion 80 of the cam Shaft 76 rides against theforward surface of the cam follower groove 81, as illustrated in FIGS.and 7. Rotation of the shaft 76 about the bearing portions 76a thereofis eiective to progressively move the cam portion 80 of the shaft 76from a rearward position as illustrated in FIG. 5 to a forward positionas illustrated in FlG. 7, thereby adjusting the relative positioning ofthe temperature sensing element 4S' and the vapor control valve 50.Accordingly, the temperature in the refrigerated compartment at whichthe bellows 51 unseats the needle valve 55 may be readily and accuratelyadjusted.

FIG. 8 illustrates a modied form of liquid carbon dioxide dischargecontrol valve wherein a diaphragm is utilized -in place of an expansionbellows. The same reference characters identify similar parts in FIG. 8and in the preceding figures. The discharge control valve 24 illustratedin FIG. 8 includes a valve body 24a having an expandable valve chamber24h' connected to receive liquid carbon dioxide 14 through the supplyconduit 15. A discharge port or valve seat opening 25' communicates withthe valve chamber 24b. The spray nozzle 23 is positioned in thedischarge port 25 and provided with a metering orifice 31 at its outerend to provide for a spray of liquid carbon dioxide. The body 24a' ofthe discharge control valve 24 is provided with a liquid carbon dioxideinlet port 33' opening into the valve chamber 24h and communicating withthe valve seat opening 25'. Moreover, the valve 24 includes a valve stemassembly 34' provided with a resilient disk or valve portion 36 seatableagainst a valve seat 37 forming the discharge port 25.

In order to move the resilient disk 36 relative to the valve seat 37 ltoclose `and open the valve stem opening the chamber Zlib', the valve stemassembly 34 is provided with a pressure dilerential responsive means,here shown -as a iiexible diaphragm 4G. One side of the diaphragm 40forms a movable wall of the chamber 24h' through which the liquid carbondioxide ows, and the other side of the diaphragm 46 forms a wall 'ofvapor chamber 42 for receiving carbon dioxide vapor 16. The resilientdisk 35 forms an end portion of the pressure responsive means 4W,thereby reducing the effective cross-sectional area of the diaphragm 40when the disk 36 is seated against the valve seat 37 A compressionspring 44 positioned in the gaseous carbon dioxide chamber 42' iseffective to bias the diaphragm 49 toward a valve closed position asillustrated in FIG. 8.

The operation of the above-described valve 24 is similar to the valve 24heretofore described in detail. Brieily, carbon dioxide vapor issupplied to the vapor chamber 42 of the valve 24 through the vaporconduit 46 and is effective to bias the resilient disk 36 against thevalve seat 37 With the valve 24 in this closed position, the pressure ofthe liquid carbon dioxide in the valve chamber 24h -Will act on thepressure dilerential diaphragm 40 on an area equal to thecross-sectional area of the diaphragm 40 less the cross-sectional areaof the discharge port 25'; the pressure of the carbon dioxide vapor inthe vapor chamber 42 will always act on an effective area of diaphragm40' equal to the cross-sectional area of ythe diaphragm 49 and will besufficient, in comb-irration with the -bias of the spring y44, tomaintain the valve 24 closed. However, if the carbon dioxide vapor isbled from the gaseous carbon dioxide chamber 42' the pressure of theliquid carbon dioxide in the valve chamber 24b will be eiective to raisethe resilient disk 36 from the valve seat 37' against the return bias ofthe vapor in the'vapor chamber i2 and the return bias lof the spring 44.Once the resilient disk 36 has lifted from the valve seat 37', thepressure of the liquid carbon dioxide now acts over the entirecross-sectional `area of the diaphragm 40', including thecross-sectional area of the discharge port 25', and the valve 2.4 isquickly opened with a snap action due to the increased effectivecross-sectional area over pressure dferential diaphragm 40 to the liquidcarbon dioxide. Similarly, once the pressure in the gaseous carbondioxide chamber 42 is permitted to build up to approximately equal thatof the pressure of the liquid carbon dioxide in the valve chamber24.19', the spring 44 will bias the valve stem assembly 34' into a valveclosed position.

In all Iof the described embodiments, fit will be seen that the liquiddischarge valvev opens and closes rapidly and positively so that thereis no appreciable time during which the pressure in the volume betweenthe disch-arge seat and the metering orice would remain lbelow thetriple point pressure of `approximately 75 lbs. per square inchabsolute. In accordance lwith the present invention, the release andadmission ofthe carbon dioxide vapor may be accomplished in Ianysuitable manner, Vfor example, a two-way vapor valve may be placedbetween the conduits 17 and 46, -as illustrated in the embodiment ofFIG. 9. The vapor valve would-then connect the conduit 46 alternatelywith the .conduit 17 and with an exhaust to atmosphere or to thecompartment l0; Referring to FiG. 9, identical components of FIG. 9 andthe preceding embodiments are identied by the same characters.Speciiically, there is illustrated a two-way vapor control valve 9dhaving a needle valve 91 which closes la vapor inlet passageway 92 whenunseated from a vapor discharge port 93. The vapor discharge port 93communicates with an exhaust opening 94. The vapor conltrol valve 90 isinstalled in the system with the vapor inlet passageway 92 connected tothe vapor supply conduit 17 and with the vapor conduit 46 from the vaporchamber 42 communicating with a valve chamber 90a thereof through anadditional port 95. The vapor control valve 90 is actuated through thetempenature sensing device 48 by the thrust pin S4 thereof which extendsthrough the vapor discharge port 93.

In operation, with the compartment 10i at the preselected lowtemperature, carbon dioxide vapor will be admitted into the vaporchamber 42 through the passageway 92, the valve chamber 91m, and port 95to close the discharge valve 24. When the temperature in the compartment1t) rises above the preselected 4setting of the temperature responsivecontrol means, the temperature sensing device 4S will be effective tounseat Vthe needle valve 91 lfrom the vapor discharge port 93, openingthe vapor discharge port 93 and closing the vapor inlet piassageway 92so that the vapor chamber 42 is exhausted through the conduit d6, port95, valve chamber 90a, vapor discharge port 93, and exhaust opening 94.

In all of the described embodiments, i-t will be seen that the liquiddischarge valve opens and closes rapidly and positively so that there isno appreciable time during which the pressure in the volume between thedischarge se-at and the metering yorifice would remain below the triplepoint pressure of approximately 75 lbs. per square inch absolute.Consequently, the liquid carbon dioxide passes through the valve and isnot converted into the solid Dry Ice which would otherwise quickly plugup the metering orice. Moreover, the discharge control valves lof thedescribed embodiment are operated by the liquid and l. scribed by Way ofillustration, many modifications will occur to those skilled in the art.It is therefore intended in the appended claims to cover all suchmodiiications as fall Within the true spirit and scope of thisinvention.

What is claimed as new and desired to be secured by Letters Patent ofIthe United States is:

1. Apparatus for refrigerating a compartment comprising a vesselcontaining liquid carbon dioxide under pressure, nozzle means openinginto said compartment for spraying liquid carbon dioxide into saidcompartment, quick acting valve means having a discharge communicatingwith said nomic, conduit means connecting said valve means and saidvessel connected to supply liquid carbon dioxide to said valve means,temperature sensing means responsive to the temperature in saidcompartment, and control means operatively associated with saidtemperature sensing means connected to actuate said valve means inresponse to the temperature in said compartment, the pressure of carbondioxide vapor in said vessel being effective to actuate said valve meansunder the control of said control means.

2. Apparatus for refrigerating a compartment comprising a tankcontaining liquid carbon dioxide under pressure, `li'uid pressureactuated quick acting valve means including a pressure differentialresponsive means, nozzle means communicating with one side of saidpressure differential responsive means and opening into said compartmentfor spraying liquid carbon dioxide into said compartment, conduit meansinterconnecting said one side and said tank for supplying liquid carbon`dioxide to said valve means, conduit means interconnecting said tankandthe other side of said pressure differential responsive means `forsupplying carbon dioxide vapor to said valve means, flow restrictingmeans in the last mentioned conduit means, temperature sensing meansresponsive to the temperature in said compantment, and control meansoperatively associated with said temperature sensing means connected tobleed carbon dioxide vapor from said other side of said pressuredifferential responsive means under the control of said. temperaturesensing means.

3. Apparatus as set forth in claim 2 above wherein a portion of said oneside of said pressure differential responsive means forms a valveportion seatable against a valve seat to close an opening in the body ofsaid valve means, and wherein said nozzle means communicates with saidopening so that when said valve portion is seated on said valve seat thepressure of the liquid carbon dioxide on said yone side ofsaidpressuresdilferential responsive means acts on the cross sectionalarea of said pressure differential responsive means less the crosssectional area of said opening and when said valve portion is unseatedfrom said valve seat :opening said pressure acts on the full crosssectional area of said pressure differential responsive means.

4. Apparatus for refrigerating a compartment comprising a tank forstoring liquid carbon dioxide under pressure, nozzle means opening intosaid compartment for spraying liquid carbon dioxide into saidcompartment, conduit means communicating between said tank and saidnozzle means for transporting liquid carbon dioxide from said tank tosaid nozzle means, quick acting valve means in said conduit meansoperable in response to the temperature in said compartment, said quickacting valve means being operable by fluid pressure, means operativelyinterconnecting said valve means and said tank to provide carbon dioxidevapor under pressure from said tank to operate said valve means, andtemperature responsive control means controlling said last ymentionedmeans.

5. Apparatus for refrigerating a compartment comprising a tankcontaining liquid carbon dioxide under pressure, fluid pressure operatedquick acting control valve means for said liquid carbon dioxideincluding a valve housing, a valve stem assembly within said housing, yapressure differential responsive member carried by said stem assemblyand sealed Iwith said housing dividing said housing into a iirst`cham-ber for Vliquid and into a second chamber for vapor, said firstchamber bein-g provided With a liquid inlet port and a liquid outletport, a valve seat Vformed in said housing `around said liquid outletport, a valve portion carried by said stem assembly and movable Withsaid stem assembly to seat against said valve seat, means biasing saidstem assembly in a direction to seat said valve portion against saidvalve seat, a vapor port communicating with said second chamber, nozzlemeans communicating with said liquid outlet port andl opening into saidcompartment for spraying liquid carbon dioxide into said compartment,conduit means interconnecting said liquid inlet por-t and said liquidcarbon dioxide in said tank for supplying liquid carbon dioxide to saidvalve means, conduit means interconnecting said tank and said vapor portfor supplying carbon dioxide vapor to said valve means, iloW restrictingmeans in the last mentioned conduit means, temperature sensing meansresponsive to the temperature in said compartment, land control meansoperatively associated with said temperature sensing means connected tobleed carbon dioxide vapor from said `second cham-ber under the controlof said temperature sensing means.

6. A quick acting control valve for liquid carbon dioxide and the likecomprising a valve housing, a valve stern assembly within said housing,-a pressure differential responsive member carried by said stem assemblyand sealed with said housing dividing said housing into a first chamberfor liquid and into a second chamber for vapor, said fir-st chamberbeing provided with a liquid inlet port and a liquid outlet port, 4avalve seat formed in said housing `around said liquid outlet pont, avalve portion carried by said stem assembly and movable with said stemassembly to seat against said valve seat, means biasing said stemassembly in a direction to' seat said valve portion against said valveseat, and a vapor port communicating with said second chamber forsupplying vapor to said second chamber and for bleeding vapor from saidsecond chamber.

7. Apparatus for refrigerating 'a compartment comprising a tankcontaining liquid carbon dioxide under pressure; iluid pressure operatedquick acting valve means including a pressure differential responsivemeans, nozzle means communicating with one side of pressure differentialresponsive means and ope-ning into said compartment for spraying liquidcarbon dioxide into said compartment; conduit means interconnecting saidone side and said tank for supplying liquid carbon dioxide to Said valvemeans; conduit means interconnecting said tank and the other side ofsaid pressure dilferential responsive means for supplying carbon dioxidevapor to said valve means; flow restricting means in the last mentionedconduit means; a temperature sensing device including a housing, anexpandable member in said housing, a temperature sensing bulb positioned.Within said compartment, conduit means interconnecting said expandablemember and said bulb, a temperature sensitive duid lling said bulb,expandable member, and conduit means, and a thrust member extending fromsaid housing operatively associated with said expandable member; a vaporcontrol valve including a valve body having a valve chamber, a vaporinlet port communicating with said chamber, a vapor outlet port forexhausting vapor from said chamber and `forming a valve seat in saidhousing, a needle valve in said housing, means biasing said needle valveagainst said seat; means provided on said temperature sensitive deviceand said vapor control valve for interconnecting said device and saidvalve with said thrust memfber engageable to unseat said needle valve inresponse to expension o-f said expandable member; and conduit meansinterconnecting said vapor inlet port and said other side of saidpressure differential responsive means.

8. A method of spraying liquid carbon dioxide into a compartmentcomprising Ithe steps of storing a quantity of liquid carbon dioxideunder pressure, supplying said liquid` carbon dioxide under pressure fordischarge into said compartment, and periodically discharging a portionof said liquid carbon dioxide from said pressure to the pressure in saidcompartment and including ,the steps of rapidly initiating the dischargeof said carbon dioxide to begin said discharge and rapidly terminatingsaid discharge of said carbon dioxide, utilizing the pressure of saidliquid carbon dioxide to eie'ct the rapid initiation of the discharge'of the said carbon dioxide and utilizing the pressure or carbon dioxidevapor to effect the rapid termination of said discharge of liquid carbondioxide.

9. A method of spraying liquid carbon dioxide into a compartmentcomprising the steps lof storing a quantity of liquid carbon dioxideunder pressure, supplying said liquid carbon dioxide under pressure fordischarge into said compartment, and periodically discharging a portionof said liquid carbon dioxide from said pressure to the pressure in saidcompartment and including the steps of rapidly initiating the dischargeof said lcarbon dioxide to begin said discharge and rapidly terminatingsaid discharge of said carbon dioxide, provid-ing a pressure dilerentialof the pressure of said carbon dioxide to eifect the rapid initiationand the rapid termination of said discharge, and controlling saidpressure differenti-al in respouse to the temperature in saidcompartment.

10. A method of spraying liquid carbon dioxide into a compartmentcomprising ythe steps of storing a quantity of liquid carbon dioxideunder pressure, 'transporting said liquid carbon dioxide under pressureor discharge into said compartment and including the steps lof passingsaid liquid carbon dioxide through a val-ve seat opening in a valve intoa discharge means and discharging the carbon dioxide through saiddischarge means into said compartment, biasing said valve toward an openposition by the pressure of the liquid carbon dioxide in s-aid valve,supplying carbon dioxide vapor under pressure 'from the stored liqu-idcarbon dioxide to said valve, biasing said valve toward a closedposition by the pressure of the carbo-r1 dioxide vapor, restricting therate of ilow of carbon dioxide vapor to said valve, `and periodicallybleeding the carbon dioxide vapor from said valve in response totemperature change in said compartment to a'ctuate' said val-ve.

y11. Apparatus -for refrigenating a compartment cornprising a vesselcontaining liquid carbon dioxide under pressure; iuid pressure operatingvalve means for spraying liquid carbon dioxide into said compartmentincluding a housing, lmeans forming a rst chamber for liquid and asecond chamber 'for vapor within said housing including a pressuredifferential responsive member disposed between them, said iirst chamberbeing provided with a 'liquid inlet port and a liquid outlet port, iirstconduit means connecting said vessel to said first chamber for supplyingliquid carbon dioxide to said first chamber, second conduit meansconnecting said vessel to said second chamber for supplying carbondioxide vapor to said second cham-ber, a valve seat fonmed in saidhousing around said liquid outlet port, a valve member movable by saidpressure differential responsive member to seat against said valve seat,said valve member being` biased toward an open position by the pressureof liquid carbon dioxide on said valve member, said valve member beingbiased toward a closed position by the pressure of carbon dioxide vaporin said second chamber, means forming a vapor port communicating withsaid second chamber, and means for periodically bleeding the carbondioxide vapor from said second chamber in response to temperature changein said compartment to aetuate said valve member toward an openposition.

References Cited in the tile of this patent UNITED STATES PATENTS1,347,689 Fitts July 27, 1920 2,172,916 Vidal Sept. 12, 1939 2,337,600Harris Dec. 126, 1943 2,475,755 Pearson July 12, 1949 2,496,816Schlumbohm Feb. 7, 1950 2,587,363 Miller Feb. 26, 1952 2,665,072 RayJan. 5, 1954 2,968,161 Bliss Jan. 17, 1961 2,988,898 f Hesson et al.Jun-e 20, 196l 3,014,664 Meyer et al Dec. 26, 196l

8. A METHOD OF SPRAYING LIQUID CARBON DIOXIDE INTO A COMPARTMENTCOMPRISING THE STEPS OF STORING A QUANTITY OF LIQUID CARBON DIOXIDEUNDER PRESSURE, SUPPLYING SAID LIQUID CARBON DIOXIDE UNDER PRESSURE FORDISCHARGE INTO SAID COMPARTMENT, AND PERIODICALLY DISCHARGING A PORTIONOF SAID LIQUID CARBON DIOXIDE FROM SAID PRESSURE TO THE PRESSURE IN SAIDCOMPARTMENT AND INCLUDING THE STEPS OF RAPIDLY INITIATING THE DISCHARGEOF SAID CARBON DIOXIDE TO BEGIN SAID DISCHARGE AND RAPIDLY TERMINATINGSAID DISCHARGE OF SAID CARBON DIOXIDE, UTILIZING THE PRESSURE OF SAIDLIQUID CARBON DIOXIDE TO EFFECT THE RAPID INITIATION OF THE DISCHARGE OFTHE SAID CARBON DIOXIDE AND UTILIZING THE PRESSURE OF CARBON DIOXIDEVAPOR TO EFFECT THE RAPID TERMINATION OF SAID DISCHARGE OF LIQUID CARBONDIOXIDE.